Bias and stereotypes are holding back gender equality in the workplace. Photograph: Dave Thompson/PA

Women have never been in a stronger position to lead, change and shape the economic, social and political landscape. The 21st century has seen a dramatic shift in "traditional" family dynamics and greater recognition of gender in legislation has helped pull apart gender-role divisions. As a result women are far more economically independent and socially autonomous, representing 42% of the UK workforce and 55% of university graduates. Yet women are still less likely than men to be associated with leadership positions in the UK: they account for 22% of MPs and peers, 20% of university professors, 6.1% of FTSE 100 executive positions, and 3% of board chairpersons. This stark inequality is consistently reflected in pay gaps, despite the introduction of the Equal Pay Act in 1975. Income inequality has risen faster in the UK than any other OCED country and today women earn on average £140,000 less than men over their working careers.

In recent reports 2.4 million unemployed women said that they want to find employment, and nine out of 10 people want to see men and women equally represented in leadership positions. If the intention to change is there, and basic social and political frameworks support women in the workforce, then we need to look beyond facts and figures to establish what other factors contribute to the gaping hole in gender equality. While statistics offer insights into current patterns and behaviours, they do not address why the skills and talents of women are not being fully utilized.

A relatively neglected factor is the role of stereotypes, reinforced by social and cultural norms, which underline certain expectations about gender. Decades of research has shown that stereotypes about men and women have a huge impact on our beliefs about how they should (or should not) behave. Consequently gender stereotypes reinforce social status and gender hierarchies: for example, surveys and experiments show that women are generally perceived as more "communal" and "loyal", whereas men are described more as "protectors" and "competent". Of course not everyone subscribes to these stereotypes, but there is evidence that men and women who behave in ways that contrast with these traditional stereotypes – such as career women or stay-at-home dads – are likely to be evaluated negatively by others. A lifetime of exposure to what women should be, how they should behave and who they should represent drives and reinforces unconscious and unseen biases.

Unconscious bias is particularly important as it arises from the implicit assumptions and unspoken attitudes, beliefs and expectations that we all have about others. Study after study has highlighted that both men and women have unconscious gender biases. For example, people view men as more capable leaders, men are rewarded more highly than women – just having a male name is more likely to get you the job. If you are a mother, your chances of getting the job are reduced by 70%. Overcoming stereotypes and unconscious bias can only be achieved if we are all willing to address our own immediate judgments and can put in place practices and procedures to mitigate their potential effects.

When we pair the psychological evidence with the economic facts, the argument for gender equality is overwhelming. Research consistently shows that groups perform to a higher standard if the gender balance is even, or when women outnumber men. For example, Catalyst research found that companies with high-level female representation on boards significantly outperformed those with sustained low representation by 84% on return on sales, 60% on return on invested capital, and 46% on return on equity. The Women's Business Council predicts that we could add 10% (that is over £150bn) to our GDP by 2030 if all the women that wanted to work were employed.

In the long term encouraging women to participate in the labour market is vital to ensure economic growth at both micro and macro level. As we face an increasingly ageing population and the resulting shortage of skilled workers, it is fundamental that we also depend on high female employment and high wage returns in order to manage the skills deficit.

We are taking bigger and bigger steps towards providing more flexible workplaces, better parental leave policies and more chances for women to get back into the workplace. But these opportunities are wasted if our stereotypes and biases distort the way we evaluate others, and often to their disadvantage.

• Abigail Player is a PhD student at the Centre for the Study of Group Processes at Kent university's school of psychology.

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